Interventional imaging of patients is an area of promising progress. Catheter-based treatments in the cardiovascular field, such as stent placing and aneurism treatment, are exceeding several million interventions per year. The benefits of these minimal invasive techniques compared to open surgery are numerous. To further reduce the risks for the patients during interventions and to open up new catheter-based treatments, the local diagnosis of the diseased cardiovascular tissue must be further improved.
Arteriosclerosis (plaque) forms an important disease affecting millions of people. Among the various types of plaque, the vulnerable plaque (sometimes call high-risk plaque) is the life threatening form, which is responsible for about 70% of fatal acute myocardial infarction and/or sudden deaths. Diagnosing and treating vulnerable plaque are both important in this respect because it requires a complete care cycle, hence there is no opportunity for treatment without diagnosis and vice versa.
Optical techniques have the unique properties of allowing detailed molecular and structural analysis of tissue while being compact and minimally invasive if integrated in catheters. For example, when a disease like arteriosclerosis is detected, knowledge of its severeness is important in order to be able to select the optimal treatment. This requires a more detailed knowledge of the diseased area. This detailed plaque inspection cannot be performed properly with current techniques like conventional angiography, magnetic resonance angiography (MRA) or computed tomographic angiography (CTA). Optical techniques are highly suitable for obtaining detailed molecular and structural information, and will improve the treatment.
Although various modalities exist to characterize plaque, methods to get detailed information in vivo on the cellular and molecular level of plaque are still underdeveloped. There are various modalities that can characterize vulnerable plaque to a certain extend (see for example Madjid et al., “Finding vulnerable arterosclerotic plaques: Is it worth the effort”, Arterioscler. Thromb. Vasc. Biol. 24 (2004) pp. 1775-1782.), but they are not able to characterize in-vivo the plaque on a cellular/molecular level.
EP1299711 discloses a method and an apparatus for examining the sub-surface microstructure of an in-vivo sample, in particular with optical coherence tomography (OCT). Radiation from a plurality of optical radiation sources travels along a first optical path. In the first optical path, a device focuses the optical radiation from each of the optical sources into a plurality of respective focal points along the first optical path to provide substantially continuous coverage of a selected portion of the first optical path. Then, a sample on the first optical path within the selected length extending into the sample is scanned along said selected portion of the first optical path and an image of the sample being examined can be obtained. This provides a solution to the problem of performing a fast scanning by OCT by a somewhat complicated lens system with multiple fibre/channels stepped in relation to one another, cf. FIGS. 1 and 2. However the lens geometry is fixed making such devices quite inflexible with respect to change of imaging depth and/or imaging technique. Another aspect of scanning the area of interest at high resolution only is that the required measuring time becomes rather large. Furthermore, OCT only provides only limited molecular information of tissue.
Hence, an improved imaging system would be advantageous, and in particular a more efficient and/or reliable imaging system for in-vivo imaging and characterization would be advantageous.